Introduction

• Sites of 1^o tumors that most commonly metastasize to bone

Ø  Breast, Lung, Prostate, Thyroid, Kidney

• Some common bone tumors and tumor-like lesions seen in general practice

Ø  osteochondroma, enchondroma, osteoid osteoma, osteomyelitis, metaphyseal fibrous cortical defect, fibrous dysplasia, metastases

• At this time, all Orthopaedic organizations recommend that bone tumors be managed only by Orthopaedic Surgeons trained and experienced in Orthopaedic Oncology and that the work be performed within a specific, specially equipped hospital.

Cartilage Neoplasia – osteochondroma, Chondroma, Chondrosarcoma

General

• cartilage neoplasms tend to occur in bones formed via endochondral ossification
• Cartilage characteristics

1)     chondrocytes – amount of cellular detail is directly related to activity

2)     normally organized maturation process

3)     peripheral: normal site of calcification and endochondral ossification

Osteochondroma

• benign hyaline cartilage lesion
• probably arises as a developmental defect of the epiphyseal plate
• one of most common primary lesions of bone
• occurs mainly in extremeties (appendicular skeleton)
• X-Ray appearance

Ø  Site: metaphysis

Ø  stalked

-        cartilage cap

-        osseous stalk

-        changes appearance with time

-        grows and bends away from the nearest joint

Ø  sessile

-        only forms a transmural cortical defect

• the cartilage cap microscopically mimics the epiphyseal (growth) plate
• Treatment

-        none unless symptomatic, growth after skeletal maturity, or cartilage cap > 2cm after skeletal maturity

• Prognosis: good; slight increased incidence of 2^o chondrosarcoma

Chondroma

• benign hyaline cartilage lesion
• arises in the medullary cavity of the bone
• tends to occur in the short tubular bones of the hands and feet.
• One of most common 1^o lesions of bone
• May be multiple as in Ollier’s Disease and Maffucci’s Syndrome (hemangiomas and chondromas)

X-RAY of chondroma

Ø  metaphysis location

Ø  lobulated +/- endosteal scalloping

Ø  radiolucent

• Gross

Ø  blue-white-grey, glistening, firm, homogenous

• MICRO

Ø  lobulated, hypercellular, disorganized hyaline cartilage, w/o significant atypia

• Prognosis – self-limited disease; slight increase of 2^o chondrosarcoma

Chondrosarcoma

• malignant
• proliferation of malignant cartilage
• Prognosis related to : grade, tumor site, surgical accessibility, and grade
• No effective adjuvant therapy; surgery is only type of treatment
• Affects the core skeleton more than the appendicular skeleton

Ø  meta-diaphysis

Ø  geographic lesion

Ø  endosteal scalloping

Ø  cortical thinning, flattening

Ø  intra-lesional calcification (rings and flecks)

Ø  uneven distribution

• GROSS

Ø  reflects the x-ray

Ø  cohesive growth pattern

Ø  grey-blue, lobulated lesion

Ø  endosteal scalloping

• MICRO

Ø  Minimal Criteria

1)     hypercellular

2)     loss of organization

3)     “increased” nuclear detail

4)     more than occasional bi-nuclear

cells

Microscopic (low power) view of Chondrosarcoma

Osseous Neoplasia – Osteoid Osteoma, Osteosarcoma

Osteoid Osteoma

• benign
• disease of limited growth potential
• distinct clinical presentation: pain, worse at night, relieved by ASA
• Cured by surgical removal of the “nidus”
• Meta-diaphyseal X-Ray of Osteoid Osteoma
• Usually on appendicular skeleton
• X-Ray

Ø  meta-diaphysis

Ø  “nidus” – radiographic name for lesion

Ø  radiolucent

Ø  surrounded by extreme amount of reactive bone

production

Ø  lesion can calcify

Ø  1-2 cm in max dimension by definition

• GROSS

Ø  berry-like, granular, ossified lesion

Ø  surrounded by a thick reactive bone

• MICRO

Ø  interweaving trabecula of osteoid and bone

Ø  lined by osteoblasts and a few osteoclasts

• Treatment

Ø  complete surgical removal with bone graft

Osteosarcoma

• Malignant
• The neoplastic cells produce osteoid and/or bone even if in small amounts
• Always the 1^o concern in any young patient with an obvious bone neoplasm involving a metaphysis or diaphysis of a long bone.
• In older patients, always suspect an underlying predisposing cause (ex. Paget’s disease)
• Must treat with CHEMO and SURGERY
• Usually occurs in the 2^nd and 3^rd decade
• Males > females
• X-Ray

Ø  metaphysis (91% of time)

Ø  highly variable

Ø  destructive – always

Ø  mixed osteoblastic/osteolytic

Ø  cortical destruction with extension into “soft tissues”                 Osteosarcoma of the tibia

Ø  “Codman’s triangle”

-        the tumor extends through cortex elevating the periosteum away from the bone.

• GROSS

Ø  highly variable

• MICRO

Ø  immature osseus matrix (with some exceptions)

Ø  subclassified by predominant matrix

MICRO: Low power of osteosarcoma

Small Cell Neoplasia – Ewing’s Sarcoma

Ewing’s Sarcoma

• unknown etiology
• special studies are used to exclude other small cell tumors
• treatment: Chemotherapy (still evolving), surgery, and radiation (being phased out)
• occurs predominantly in 1-3 decades
• more common in lower extremity
• Prognosis – 60% long term survivors
• X-Ray

Ø  mixed lytic/blastic

Ø  ill defined intramedullary component

Ø  moth eaten permeative pattern

Ø  “onion skin” periosteal reactive bone

Ø  large, disproportionate soft tissue mass

• MICRO Low power of Ewing’s Sarcoma

Ø  proliferation of uniform, monotonous small cells that have minimal cytoplasm

Ø  nuclei have uniform, finely distributed chromatin

Ø  cytoplasm have abundant glycogen (PAS+)

Fibrous Neoplasia – Fibrous Cortical Defect, Fibrous Dysplasia

Fibrous Cortical Defect

• benign
• fibro-histiocytic proliferation
• Therapy – avoid whenever possible because it is self-limited and will spontaneous heal at skeletal maturity
• 1^st & 2^nd decades
• tends to occur in long bones
• X-Ray

Ø  meetaphysis

Ø  eccentric, sub-cortical

Ø  soap bubbles

Ø  sclerosis at interface of lesion with uninvolved cancellous bone.

• MICRO

Ø  “spindle cells”

Ø  foamy macs

Ø  hemosiderin deposition

Ø  chronic inflammatory infiltrate

Fibrous Dysplasia

• fibro-osseous lesion
• can be mono- or polystotic (if polystotic can be associated with a # of syndromes – Albright’s syndrome)
• Treatment – dependent on clinical setting
• 1^st – 3^rd decades
• random skeletal distribution
• X-Ray

Ø  meta-diaphysis; radioopaque, “shepard’s crook” deformity of proximal femur

• HISTO

Ø  no osteoblasts lining the woven bone

Ø  the trabecula looks like “C’s”, “W’s”, and “U’s”  — CWU

Tags: Chondroma, Chondrosarcoma, enchondroma, endosteal scalloping, Ewing's Sarcoma, Fibrous Cortical Defect, fibrous dysplasia, geographic lesion, meta-diaphysis, metaphyseal fibrous cortical defect, Metastases, osteochondroma, osteoid osteoma, osteomyelitis

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